The present invention relates to a heat generator that is used as an auxiliary heat source for vehicles. More particularly, the present invention pertains to a heat generator that generates heat by shearing viscous fluid in a heating chamber with a rotor and transmits the generated heat to fluid such as engine coolant.
Typically, vehicles include hot-water type heaters, which have a heater core located in a heating duct. The heater core is supplied with engine coolant. Specifically, coolant is sent to the heater core after cooling the engine.
The heater core uses heat from the coolant to warm air in the duct. The warmed air is then supplied to the passenger compartment.
However, diesel engines and lean burn type engines have a relatively low heating value and thus are not able to heat engine coolant to a sufficient level. It is difficult to maintain the temperature of the coolant in the heater core at a predetermined temperature (for example, 80.degree. C.). Therefore, hot-water type heaters deliver relatively little heat when mounted on vehicles having diesel engines or lean burn type engines.
In order to solve this problem, a heat generator located in a fluid circuit of engine coolant has been proposed for heating engine coolant. The heat generator includes a heating chamber and a heat exchange chamber, which are defined in a housing. The heater also includes a rotor, which is accommodated in the heating chamber and is rotated by the drive force of the engine. The rotor rotates to shear viscous fluid (for example, silicone oil having a high viscosity) in the heating chamber for generating heat based on fluid friction. The generated heat is used to heat circulating fluid (engine coolant) in the heat exchange chamber. The heated circulating fluid is used to warm the passenger compartment.
It is important to improve the efficiency of heat transfer from the heating chamber to the heat exchange chamber. Also, if the housing has a special structure for improving the heat transfer efficiency, it is important to stabilize the quality of the individual products in order to put the housing to practical use.